DHCP - WLAN behaviour of Windows Notebooks

lc chilli at silverserver.at
Sat Sep 8 16:48:28 UTC 2007 

Hi David,

>
> some questions:
>
> - What version of chilli are you using? Check your root crontab for  
> any chilli init script calls with argument "arping" - it's a  
> feature, actually, I will completely remove in the next release. If  
> you're using 1.0.7, it shouldn't be an issue (the init script no  
> longer has the feature).
>

I use 1.0.7 on all systems and no, arping is not used.

> - Are your WiFi clients using any client software (a smart-client  
> or that sort of thing)? Maybe running something in the background  
> (boingo, whisher, whatever)?

I have no way to know what the clients use (all public places).  
However once I had the chance to meet a client on site who had this  
problem. He was using a Sony notebook. I checked - old drivers. So I  
updated his wireless drivers (Intel WLAN hardware) to the latest  
version - it didn't improve the situation. He did not use a smart- 
client, just the standard one which is built-in Win XP (SP2).

>
> - Have you tried using 'uamanyip' to see if that makes any difference?

Not yet, I will try it on one heavy-use location.

>
> - Do you do any kind of signal scanning from your AP or dynamic  
> changing of settings?

No.
>
> It's an interesting problem - in the client. I think chilli does  
> the right thing upon getting a DHCP release... but would be  
> interesting for it to reserve the IP for a short time.
>
I also think it is the client who triggers this problem and this  
means there is nothing much we can do on that end. IP reservation for  
a short time could be a work-around. As an additional option it would  
be interesting if chilli would delay closing a session for this short  
time.

FYI: I use the same patched version of OpenWRT WR you are using for  
Coova AP. As you wrote in another mail this version has some issues,  
so it is thinkable that it misbehaves on the wireless side in a way  
that some clients get confused and disassociate. I don't believe this  
since it is a minority of clients that have this problem but who  
knows. The reason I still use it is because it uses the stable wl  
driver (the one in official WR sometimes causes kernel panics).

Does anyone else who is using OpenWRT have noticed this issue?

Thanks,
lc


> David
>
> On 9/8/07, lc <chilli at silverserver.at> wrote:
> I had also a small e-mail conversation about the following with David
> (thanks for keeping chilli alive!) - but I still do not know how this
> "problem" can be dealt with.
>
>
> It seems that there are machines that - for no obvious reason -
> disassociate and reassociate to the AP even when they signal quality
> is excellent and no other disturbing radio exists. This seems to
> happen intentionally because the client seems to release the DHCP
> address before disassociating. And this is why chilli releases the
> address and closes the session. If the client would just lose the
> connection and reassociate, chilli wouldn't know about it unless the
> DHCP lease time has been reached (=no problem).
>
> After such a client re-associates, chilli hands out a new IP address
> and the user has to log-in again. While the re-login could be handled
> automatically (so the user won't notice it) the new IP address is a
> problem - existing connections (e.g. google mail etc) get interrupted.
>
> I have noticed this behaviour on Windows notebooks. The user can also
> see it because at the Windows task bar a message pops up telling the
> user that he is now connected to the WLAN xyz although this is the
> very same WLAN he has been already using.
>
> I see this behaviour on many locations, and I also see that it does
> not happen with all clients. e.g. on the same location at the same
> time one client behaves like in the log below while others stay
> connected for hours without any interruption. This is why I believe
> the client's machine is the cause.
>
> Here is a log showing that there are only a few seconds between the
> releasing of the address and handing out a new address for the same
> client.
>
> Chilli-Log:
> Jul 26 14:29:20 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.25
> Jul 26 14:33:09 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.25
>
> Jul 26 14:33:12 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 14:33:12 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.27
> Jul 26 14:35:42 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.27
> Jul 26 15:03:30 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.27
>
> Jul 26 15:06:36 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 15:06:36 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.30
> Jul 26 15:12:55 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.30
>
> Jul 26 15:13:30 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 15:13:30 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.31
> Jul 26 15:14:41 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.31
> Jul 26 15:19:49 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.31
>
> Jul 26 15:23:22 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 15:23:22 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.33
> Jul 26 15:28:24 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.33
>
> Jul 26 15:30:42 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 15:30:42 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.34
> Jul 26 15:32:54 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.34
> Jul 26 15:42:15 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.34
>
> Jul 26 15:42:17 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 15:42:17 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.36
> Jul 26 15:44:28 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.36
> Jul 26 15:49:39 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.36
>
> Jul 26 15:50:00 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 15:50:00 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.37
> Jul 26 15:52:07 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.37
> Jul 26 16:29:56 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.37
>
> Jul 26 16:30:18 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 16:30:18 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.40
> Jul 26 16:36:48 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.40
> Jul 26 16:50:15 OpenWRT kern.info chillispot[841]: chilli.c: 2690:
> DHCP addr released by MAC=00-18-DE-77-9B-43 IP=192.168.100.40
>
> Jul 26 16:51:42 OpenWRT kern.notice chillispot[841]: chilli.c: 2608:
> New DHCP request from MAC=00-18-DE-77-9B-43
> Jul 26 16:51:42 OpenWRT kern.notice chillispot[841]: chilli.c: 2570:
> Client MAC=00-18-DE-77-9B-43 assigned IP 192.168.100.41
> Jul 26 16:55:22 OpenWRT kern.notice chillispot[841]: chilli.c: 2905:
> Successful UAM login from username=00-18-DE-77-9B-43 IP=192.168.100.41
>
> So the question is:
>
> Does anybody know what triggers this behaviour of Windows (maybe some
> energy saving issue which works in a weird way)?
> Is there a way to make chilli temporarily bind an IP address to a mac
> address so that it would re-assign the same IP to the same client MAC
> within a certain timeframe?
>
> Thanks,
>
> lc
>
>
> Am 15.08.2007 um 10:20 schrieb Yannick Deltroo:
>
>
> > Alex,
> >
> > I've seen that you've changed the DHCP range of IPs from the  
> default.
> > Check that the three parameters net/dynip/statip are correctly  
> set (in
> > particular the netmask part).
> >
> > Also check that the lease parameter is not too short for the client
> > operating system to accept the DHCP lease returned by Chilli.
> >
> > By the way, Chillispot is going to NAT your public addresses in the
> > default configuration.
> > For more info, see this thread,
> > http://coova.org/phpBB3/viewtopic.php?
> > f=4&t=157&sid=6d5907c41c5aa11b528345295892dff9
> >
> > Cheers
> >
> > On 8/15/07, Alex Nderitu <anderitu at africaonline.co.ke> wrote:
> >
> >>
> >>  Hi All,
> >>  I have a problem where wireless clients are not allocated dhcp
> >> addresses on accessing chillispot. However from the log files I
> >> can see chillispot is issuing the addresses on accessing the
> >> wireless network. Has anyone come across this and whats the work
> >> around.
> >>
> >>  Logs from chilli
> >>  -----------------------
> >>  Aug 14 15:40:03 hotspot chillispot[7333]: chilli.c: 3082: DHCP
> >> addr released by MAC=00-16-6F-C3-7E-5F IP= 41.207.76.34
> >>  Aug 14 15:40:05 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-16-6F-C3-7E-5F
> >>  Aug 14 15:40:05 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-16-6F-C3-7E-5F assigned IP 41.207.76.35
> >>  Aug 14 15:40:18 hotspot chillispot[7333]: chilli.c: 3082: DHCP
> >> addr released by MAC=00-16-6F-C3-7E-5F IP= 41.207.76.35
> >>  Aug 14 15:40:21 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-16-6F-C3-7E-5F
> >>  Aug 14 15:40:21 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-16-6F-C3-7E-5F assigned IP 41.207.76.36
> >>  Aug 14 15:41:31 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-19-D2-30-B3-A1
> >>  Aug 14 15:41:31 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-19-D2-30-B3-A1 assigned IP 41.207.76.37
> >>  Aug 14 15:45:49 hotspot chillispot[7333]: chilli.c: 3082: DHCP
> >> addr released by MAC=00-16-6F-C3-7E-5F IP=41.207.76.36
> >>  Aug 14 15:45:51 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-16-6F-C3-7E-5F
> >>  Aug 14 15:45:51 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-16-6F-C3-7E-5F assigned IP 41.207.76.38
> >>  Aug 14 15:48:32 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-16-6F-55-01-21
> >>  Aug 14 15:48:32 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-16-6F-55-01-21 assigned IP 41.207.76.39
> >>  Aug 14 15:49:10 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-06-F4-0D-4B-DA
> >>  Aug 14 15:49:10 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-06-F4-0D-4B-DA assigned IP 41.207.76.40
> >>  Aug 14 15:52:12 hotspot chillispot[7333]: chilli.c: 3082: DHCP
> >> addr released by MAC=00-16-6F-C3-7E-5F IP= 41.207.76.38
> >>  Aug 14 15:52:14 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-16-6F-C3-7E-5F
> >>  Aug 14 15:52:14 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-16-6F-C3-7E-5F assigned IP 41.207.76.41
> >>  Aug 14 15:53:46 hotspot chillispot[7333]: chilli.c: 3082: DHCP
> >> addr released by MAC=00-16-6F-C3-7E-5F IP= 41.207.76.41
> >>  Aug 14 15:53:53 hotspot chillispot[7333]: chilli.c: 3082: DHCP
> >> addr released by MAC=00-19-D2-30-B3-A1 IP=41.207.76.37
> >>  Aug 14 15:53:59 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-16-6F-C3-7E-5F
> >>  Aug 14 15:53:59 hotspot chillispot[7333]: chilli.c: 3011: Client
> >> MAC=00-16-6F-C3-7E-5F assigned IP 41.207.76.43
> >>  Aug 14 15:55:04 hotspot chillispot[7333]: chilli.c: 3082: DHCP
> >> addr released by MAC=00-16-6F-C3-7E-5F IP=41.207.76.43
> >>  Aug 14 15:55:06 hotspot chillispot[7333]: chilli.c: 3041: New
> >> DHCP request from MAC=00-16-6F-C3-7E-5F
> >>
> >>
> >> --
> >>
> >>  Regards,
> >>
> >>  Alex Nderitu
> >>  Systems Administration
> >>  Africa Online, Kenya
> >>  Tel: +254 (20) 27 92 253
> >>  Fax: +254 (20) 27 100 10
> >>  Email: anderitu at africaonline.co.ke
> >>  AIM: nderitualex
> >>
> >>
> >>    A member of the Telkom South Africa Group
>
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